In conventional households, mattresses are used primarily only during the night. Such mattresses typically are made of a cloth fabric covering an inner box spring. However, such conventional box spring type mattresses are not acceptable for use in institutional facilities, where foam mattresses are used and have the advantage of reducing tissue trauma, such as bed sores, which result from the prolonged lying on mattresses. A number of foam mattresses for use in such institutional environments have been designed. Typically, the foam mattresses are enclosed by a cover made from a material that is impervious to passage of water or other liquids, such as urine, that typically would be experienced in the hospital environment, as well as being anti-bacterial and resistant to flame.
In a hospital environment there is a need to be able to replace component parts of a mattress which may be damaged or contaminated. For example, a sharp instrument, such as a needle, could pierce the cover and permit contaminated fluids to enter into the interior of the mattress. In such circumstance it would be desirable to replace the top cover, and the foam insert. However, in other instances, only the external cover may be damaged and the foam may still be useable. Finally, there are circumstances where only the foam may need to be replaced, such as where the foam may have been compressed during use by a prior patient. In such a case, the cover may remain perfectly usable.
There have been mattresses with component parts which may be interchanged with one another so that the entire mattress does not have to be disposed of in the above circumstances. B. G. Industries, Inc., has sold a mattress which had an internal foam upper and a lower layer, the upper layer having a cut out portion around its periphery forming a projecting segment that fit within a corresponding depression formed in the bottom foam layer. The foam pieces were enclosed by top and bottom covers attached by zippers to corresponding zipper assemblies permanently attached to the upper mattress layer.
Manufacturing such a mattress was time consuming and expensive. Further, it was bulky to ship since the two separate foam layers had to be separated during shipment. Typically a mattress of this nature is rolled up and shipped in a cylinder, conserving space. This prior art mattress did not permit the easy replacement of the components.